Image sensor with a cross-wafer capacitor
One or more cross-wafer capacitors are formed in an electronic component, circuit, or device that includes stacked wafers. One example of such a device is a stacked image sensor. The image sensor can include two or more wafers, with two wafers that are bonded to each other each including a conductive segment adjacent to, proximate, or abutting a bonding surface of the respective wafer. The conductive segments are positioned relative to each other such that each conductive element forms a plate of a capacitor. A cross-wafer capacitor is formed when the two wafers are attached to each other.
1. An image sensor, comprising:
a first wafer including a first conductive segment and a second conductive segment; and
a second wafer attached to the first wafer and comprising:
a third conductive segment positioned adjacent to the first conductive segment to produce a first cross-wafer capacitor; and
a fourth conductive segment positioned adjacent to the second conductive segment to produce a second cross-wafer capacitor;
wherein the first and the second conductive segments are directly connected to a common node, and the third and the fourth conductive segments are connected to discrete signal lines connected to one or more discrete circuits.
2. The image sensor as in claim 1 , wherein the first wafer and the second wafer are attached to each other with copper-to-copper direct bonding.
3. The image sensor as in claim 1 , further comprising a first dielectric material between the first and the third conductive segments and a different second dielectric material between the second and the fourth conductive segments.
4. The image sensor as in claim 1 , wherein:
the first and the second conductive segments are positioned at a first bonding surface of the first wafer;
the third and the fourth conductive segments are positioned at a second bonding surface of the second wafer; and
the image sensor further comprises a layer of dielectric material positioned between the first and the second bonding surfaces.
5. The image sensor as in claim 1 , wherein the first wafer comprises a sensor wafer and the second wafer comprises a circuit wafer.
6. The image sensor as in claim 5 , further comprising a third wafer attached to the second wafer, wherein
the second wafer comprises a fifth conductive segment;
the third wafer comprises a sixth conductive segment positioned adjacent to the fifth conductive segment to produce a third cross-wafer capacitor;
a first circuitry is connected between the third conductive segment and the fifth conductive segment; and
a second circuitry is connected to the sixth conductive segment.
7. The image sensor as in claim 6 , further comprising a third circuitry connected to the fourth conductive segment.
8. The image sensor as in claim 6 , wherein
the fifth conductive segment is positioned at a third bonding surface of the second wafer;
the sixth conductive segment is positioned at a fourth bonding surface of the third wafer; and
the image sensor further comprises a layer of dielectric material positioned between the second and the third bonding surfaces.